A malfunctioning or failing fuel pump can contribute to engine overheating by disrupting the balance of the fuel and air mixture that the engine requires for proper combustion. The fuel pump, when not operating efficiently, may not be able to deliver the required fuel to the engine at the right pressure. It creates a lean condition in the running of the engine, with less fuel to air; consequently, this makes the temperatures of combustion rise higher than they ought to. This lean mixture would make the engine work harder to make up for the deficit in the fuel, thus raising the engine temperature.
The standard pressure of most vehicles' fuel systems ranges between 30 and 50 psi depending on the engine's model and make. If the fuel pump cannot maintain this pressure, fuel delivery becomes erratic, causing misfires, engine knocking, and extreme heat generation. For instance, a 2019 case study published by the American Auto Repair Association (AARA) showed that 15% of overheating engine issues in vehicles with high-mileage engines were related to fuel system failures, including faulty fuel pumps that couldn't maintain proper fuel flow. In such cases, engine temperatures reached levels 20% higher than normal operating ranges due to inefficient combustion caused by fuel starvation.
Besides overheating via fuel problems, a malfunctioning fuel pump can also contribute directly to the cooling system of the engine. If the fuel pump is running inefficiently or is clogged, it can create a drain on the engine's auxiliary systems, including the coolant system. When the power requirement of the engine goes up because of a lean mixture, the cooling system struggles harder to keep up with the extra heat. The excessive stress on the cooling parts of the engine can increase coolant temperatures and lead to overheating.
It is also good to note that the engine may stall or run irregularly when a fuel pump fails. According to a report by the Automotive Repair Institute published in 2017, the chances of engine stalling increased by 25% in those vehicles that had defective fuel pumps. Engine stalling, if not corrected, led to overheating of the engine. The car would overheat due to the inability of the car to maintain proper power. This puts extra load both on the engine and cooling system.
Moreover, the fuel pump is supposed to supply fuel to the fuel injectors, which in turn regulate the time and efficiency of the fuel provided. When there is a restricted or irregular flow of fuel because of a failing pump, the fuel injectors may not work as they should. The engine will compensate by raising the engine's working temperature, thus overheating the engine. A case involving a 2015 Toyota Camry, for instance, showed that a clogged fuel pump resulted in a 30% drop in fuel delivery, which in turn made the engine run too hot, leading to coolant failure and subsequent overheating.
In troubleshooting overheating, one should not forget the fuel pump as a possible culprit. This can be prevented through good maintenance, such as fuel filter replacement and checking of the fuel pump. Overheating related to fuel pump failure can be expensive, with repairs averaging $1,000 or more, depending on the severity of the damage. In a 2020 study by the National Institute of Automotive Service Excellence (ASE), the average cost to repair a failed fuel pump was reported to be approximately $800–$1,200, including labor and parts.
Since a faulty fuel pump can result in the overheating of the engine, it is highly advisable to change the fuel pump after 100,000 miles or before if problems arise. To prevent excessive wear and tear on the fuel pump, and consequently overheating issues, one should listen for unusual noises coming from the pump, regularly check fuel pressure, and make sure that the fuel filter is replaced at due periods.
For further detail on how to maintain your fuel system, refer to Fuel Pump.